The present invention relates to a visual examination apparatus and a visual examination method for a semiconductor device having a substantially rectangular package.
When a visual examination is performed on a semiconductor device comprising a QFP (Quad Flat Package) in which plural leads are extended from each side surface of a substantially rectangular package, it has been hitherto adopted that an image reading device such as a CCD camera or the like is disposed at the side of the package and the deformation of leads, the pitch between leads, and so forth are examined on the basis of the image of the side surface side of the package which is taken in by the image reading device.
In the semiconductor device visual examination based on the image reading device disposed at the side of the package as described above, an image on each of four side surfaces of the substantially rectangular package is picked up, and thus after an image on a first side surface is picked up, the package or the image reading device is rotated by 90.degree. to pick up an image on a second side surface. This operation is repeated to pick up the respective images on the four side surfaces, and it is examined through predetermined image processing whether leads extending from each side surface are good or not.
Further, with respect to the warp, and so forth of the package, the outer dimension of the package is measured by using a laser measuring machine or the like, and the calculation is performed on the basis of the measurement result to determine the warp amount.
Recently, a BGA (Ball Grid Array) type semiconductor device in which a plurality of ball-shaped electrodes are arranged at the lower surface of a package and a CSP (Chip Size Package) type semiconductor device have been frequently utilized from the viewpoint of enhancement of mount density.
In such a BGA or CSP type semiconductor device, the ball-shaped electrodes are extended from the lower surface of the package. Therefore, reflection light from each electrode has a great effect, and thus it is very difficult to perform various examinations on the basis of pickup images. Particularly when a ball interval is examined, the ball and the package are slightly discriminated from each other on the basis of the pickup image, resulting in reduction in examination precision.
Further, there is a problem that the measurement of the outer dimension of the package on the basis of the laser measuring machine or the like needs a long processing time, and it is liable to be effected by the surface state of the package.